Blink Led using MQTT in arduino

Question

I have to implement a prototyping scenario that blink LED in the arduino with MQTT protocol. I already tried with several MQTT libraries but non of them not work perfectly. Connection to the MQTT broker working successfully but when I publish the message with topic which I set in arduino not blink the LED. Arduno have to publish a message when it successfully connect but this publishing part also not working

this is my code

    #include <SPI.h>
#include <Ethernet.h>
#include <PubSubClient.h>

// Set the MAC address
byte mac[]    = {  0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED };
IPAddress ip(192, 168, 1, 100);
IPAddress server(192, 168, 1, 20);

// Set what PINs our Led's are connected to
int redPin = 13;                
//int greenPin = 6;
//int bluePin = 7;

// Set a generic code that will trigger our Blue Led
// think of this as a set of codes for automation you might write
byte triggerRed[13] = "12345";

// handles messages that are returned from the broker on our subscribed channel
void callback(char* topic, byte* payload, unsigned int length) {

  Serial.print("New message from broker on topic:");
  Serial.println(topic);

  Serial.print("Payload:");
  Serial.write(payload, length);



  // Check and see if our payload matches our simple trigger test
  if ((length == 5) & (memcmp(payload, triggerRed, 5) == 0) )
  {
    //blink(redPin);

  }

}
EthernetClient ethClient;
PubSubClient client(ethClient);
// Fire up our PubSub client
//PubSubClient client(server, 1883, callback);

void setup()
{

  // Open serial communications
  Serial.begin(9600);

  client.setServer(server, 1883);
  client.setCallback(callback);

  // Setup our Leds
  pinMode(redPin, OUTPUT);
 // pinMode(greenPin, OUTPUT);
 // pinMode(bluePin, OUTPUT);

  // attempt a DHCP connection
  Serial.println("Attempting to get an IP address using DHCP:");
  if (!Ethernet.begin(mac)) 
  {
    // if DHCP fails, start with a hard-coded address:
    Serial.println("failed to get an IP address using DHCP, trying manually");
    Ethernet.begin(mac, ip);
  }

  Serial.print("My address:");
  Serial.println(Ethernet.localIP());

  // Connect to Broker, give it arduino as the name
  if (client.connect("arduino")) {

    // Good, we connected turn on the red led
    digitalWrite(redPin, HIGH);

    // Publish a message to the status topic
    client.publish("status","Arduino is now online");

    // Listen for messages on the control topic
    client.subscribe("ultra");
  }

}

void loop()
{
  client.loop();
}

// Anything with flashing lights.
void blink(int targetLed) 
{
  digitalWrite(redPin, HIGH);

}

how can I fix this ?

Did you try to run example sketch from Arduino MQTT library? I recommend you to put client connection routine in a loop. Why not try to connect to a public server on web, for example test.mosquitto.org before connecting to a local one? — Vladimir T
– Vladimir T, Commented Apr 24, 2016 at 12:27
I already test with test.mosquitto.org but that didn't work. What you mean put client connection in loop ? LED blink when I publish a message with correct topic. but I need it to keep it "ON" always — rafalefighter
– rafalefighter, Commented Apr 24, 2016 at 12:35

Vladimir T · Accepted Answer · 2016-04-24 12:48:45Z

0

Put connection routine in a loop and try with test.mosquitto.org first. Here is code that works for me (Ethernet shield hardware):

definitions:

#define CLIENT_NAME "myclientname"
#define TOPIC "mytopic"
byte mac[]    = {  0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED };
IPAddress ip(192, 168, 1, 105);
IPAddress server(85, 119, 83, 194);// test.mosquitto.org
#define MQTT_PORT 1883
IPAddress myDns(8, 8, 8, 8);
EthernetClient ethClient;
PubSubClient client(ethClient);

setup:

client.setServer(server, MQTT_PORT);
client.setCallback(callback);
Ethernet.begin(mac);

loop:

if (!client.connected()) {
            reconnect();
        }
client.loop();

reconnect routine

void reconnect() {
    if (millis() - reconnectionTimer >reconnection_period){// Loop until we're reconnected
        reconnectionTimer = millis();
        if (!client.connected()) {
            // Attempt to connect
            if (client.connect(CLIENT_NAME)) {
                client.subscribe(TOPIC);
            }
            else {
                Serial.print(client.state());
                Serial3.print(client.state());
            }
        }
    }
}

update for blink:

void blink(){
  digitalWrite(led, LOW);
  delay(500);
  digitalWrite(led, HIGH);
}

edited Apr 24, 2016 at 12:48

answered Apr 24, 2016 at 12:40

Vladimir T

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1 Comment

Vladimir T Over a year ago

This is code for establishing connection. You may have issue with connection, not with led. From your code i see you have commented out blink routine. And anyway this routine not contains code for blinking.

Felipe Santa · Accepted Answer · 2018-07-14 08:49:30Z

0

I lost a lot of time because i had the problem with the mqtt server. ensure that your server is using mqtt protocol, because i was using ws protocol and any library that I tried doesn't works with this protocol

answered Jul 14, 2018 at 8:49

Felipe Santa

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